Processing machines for processing coil material, such as spring machines, bending machines, nailing machines, leveling machines, etc. operate, as a rule, together with reels, which hold a supply of coil material, such as wire. Starting with said coil, e.g., the wire is fed to the processing machine, which is downstream of the reel. The reel is usually driven at a constant rotation speed, whereby the rotation speed of the reel determines how much wire is unwound from the coil and fed to the downstream processing machine. Thereby, the reel rotation speed can be adjusted via a tensioning device, such as a deflection arm, which is attached to the reel, spring-pretensioned in a deflection direction, effective up to a maximum deflection, and adjusted to the decreasing diameter of the coil to be processed or, adjusted in case of greater or smaller than desired wire tension, whereby, e.g., in case of a radially outward moving deflection arm, the reel rotation speed is increased, or in case of an unchanged position of the deflection arm is set freely revolving, or in case of a radially inward swiveling of the deflection arm, an acceleration of the reel rotation speed is achieved (see DE 30 10 508 C2).
It has become evident that problems occur rarely with such processing machines with a sufficiently constant infeed speed or with a relatively evenly intermittent, moderately fluctuating at its temporal mean, infeed speed profile of the machine infeed (such as in tension spring and compression spring machines, or special processes, ring winding machines and the like), since the reel control is sufficiently capable of following the requirements of the processing machine via dancer, deflection arm and/or workpiece storage (e.g., multiple redirections).
However, this is no longer the case with processing machines with a regularly intermittent but greatly fluctuating infeed speed (e.g., tension spring and compression spring machines with special processes) and with machines with irregularly intermittent infeed speed profile (such as leg spring machines, wire-bending and pipe-bending machines), which frequently experience problems because the reel control via dancer, deflection arm and/or storage cannot follow the requirements of the processing machine, i.e., the parts-specific infeed speed profile.
For example, the control utilized in the arrangement in DE 30 10 508 C2 is not capable of achieving a sufficiently quick reaction of the reel with high dynamic processing machines.
In the arrangement in DE 34 22 499 A1, a transducer attached to the infeed rollers of the downstream-positioned processing machine is used for controlling the speed of the reel. However, this has the disadvantage that the reel rotation is always a reaction to the infeed movement, which, once again, does not allow for a sufficiently quick and satisfactory adjustment of the movement profile of the reel rotation to the machine infeed.
In the arrangement described in DE 32 35 217 A1, two deflection arms are provided for compensation of larger differences in the infeed speed. However, this requires a huge mechanical effort and great retooling effort in order to adjust the reel to new parts and/or movement profiles, whereby in this known arrangement, a control process for the reel drive is only triggered if the amount of wire demanded by the infeed of the processing machine changes. As a result, the reel rotation speed is once again a reaction to the infeed speed.
With the known arrangements of a control for the reel drive of a wire processing machine, the requirements can be such that the reel can rotate as continuously and evenly as possible without simultaneously limiting the high dynamic of the processing machine, which cannot be sufficiently achieved with the redirections, dancers, storage (deflection arms) and the like utilized with known reels, resulting in an unsteady motion of the reel, kinks in the wire or greatly fluctuating tensile loading in the wire. However, these effects are quite unfavorable for the accuracy and reproducibility of the actual processing tasks on the wire and/or pipe.
Therefore, according to the invention, a device shall be suggested for the control of the drive of a reel whereby the aforementioned disadvantages shall be largely avoided.